Internal combustion engine

Abstract

An internal combustion engine, for motor vehicles having a direct fuel injection and externally supplied ignition, which has at least one combustion chamber enclosed between a cylinder head and a reciprocating piston displaceable in a cylinder bore, the combustion chamber being closable by at least one inlet valve for air aspiration. To attain extensive homogeneity of the mixture formation in direct fuel injection that assures reliable, thorough combustion of the mixture, the combustion chamber is preceded at its upper end by a chamber, which opens toward the combustion chamber and has an inside cross section that is substantially smaller than the combustion chamber and increases steadily toward the combustion chamber. The injection and ignition take place in the chamber.

We claim: 
     
       1. An internal combustion engine, for motor vehicles, comprising a direct fuel injection and externally supplied ignition, at least one combustion chamber (10) enclosed between a cylinder head (11) and a reciprocating piston (14) displaceable in a cylinder bore (12), the combustion chamber being closable by at least one inlet valve (15) for air aspiration, the combustion chamber (10) is preceded at an upper end by a chamber (10), which opens toward the combustion chamber (10) and has an inside cross section that is substantially smaller than the combustion chamber (10), and that the injection and ignition take place in the chamber (17), and turbulence edges (26) are provided in the chamber 17 for making fuel and air turbulent. 
     
     
       2. An internal combustion engine in accordance with claim 14, in which the chamber (17) is embodied as bell-shaped and its volume amounts to approximately 30 to 50% of the minimum combustion chamber volume present at top dead center of the reciprocating piston (14). 
     
     
       3. An internal combustion engine in accordance with claim 1, in which the chamber (17) is embodied in the cylinder head (11). 
     
     
       4. An internal combustion engine in accordance with claim 1, in which a virtually symmetrical depression (24) is formed in the middle of the end wall of the reciprocating piston (14) that defines the combustion chamber (10), and this depression, together with the combustion chamber (10), adds to the bell shape of the chamber (17) to make a pear shape. 
     
     
       5. An internal combustion engine in accordance with claim 1, in which the fuel injection is controlled such that a fuel-air mixture formation takes place in the chamber (17) at idling and lower partial load, and in the chamber (17) and the combustion chamber (10) at upper partial load and full load. 
     
     
       6. An internal combustion engine in accordance with claim 5, in which at idling and lower partial load a correspondingly small fuel quantity is injected if the reciprocating piston (10) is located approximately at bottom dead center, and that at upper partial load and full load a correspondingly large fuel quantity is injected when the reciprocating piston (14) is moved downward out of its top dead center in the intake stroke. 
     
     
       7. An internal combustion engine in accordance with claim 6, in which in a homogeneous lean operating mode or in operation with exhaust gas recirculation at upper partial load and full load, a further small fuel quantity is injected when the reciprocating piston (14) is located at approximately its bottom dead center. 
     
     
       8. An internal combustion engine in accordance with claim 1, which includes an injection nozzle (18) for the fuel injection and a spark plug (20) with an ignition electrode (201, 202) for the ignition, the injection nozzle and the spark plug being disposed in the cylinder head (11), the spark plug (20) and the injection nozzle (18) are oriented such that the ignition electrodes (201, 202) protruding into the chamber (17) are located outside the injection stream (21) of the injection nozzle (18). 
     
     
       9. An internal combustion engine in accordance with claim 3, which includes an injection nozzle (18) for the fuel injection and a spark plug (20) with an ignition electrode (201, 202) for the ignition, the injection nozzle and the spark plug being disposed in the cylinder head (11), the spark plug (20) and the injection nozzle (18) are oriented such that the ignition electrodes (201, 202) protruding into the chamber (17) are located outside the injection stream (21) of the injection nozzle (18). 
     
     
       10. An internal combustion engine in accordance with claim 8, in which the spark plug (20) and the injection nozzle (18) are combined into one structural unit (22), which is inserted interchangeably into the cylinder head (11). 
     
     
       11. An internal combustion engine in accordance with claim 8, in which the spark plug (20) and the injection nozzle (18) are disposed biaxially or coaxially. 
     
     
       12. An internal combustion engine in accordance with claim 10, in which the spark plug (20) and the injection nozzle (18) are disposed biaxially or coaxially. 
     
     
       13. An internal combustion engine in accordance with claim 11, in which if the spark plug (20) and injection nozzle (18) are disposed coaxially, the injection opening (19) of the injection nozzle (18) is disposed centrally. 
     
     
       14. An internal combustion engine in accordance with claim 1, in which the injection nozzle (18) is embodied controllably in terms of a reach and cross section of its injection stream (21), and that at idling and lower partial load, a short reach and a wide cross section and at upper partial load and full load a long reach and a narrow cross section of the injection stream (21) is set. 
     
     
       15. An internal combustion engine, for motor vehicles, comprising a direct fuel injection and externally supplied ignition, at least one combustion chamber (10) enclosed between a cylinder head (11) and a reciprocating piston (14) displaceable in a cylinder bore (12), the combustion chamber being closable by at least one inlet valve (15) for air aspiration, the combustion chamber (10) is preceded at an upper end by a bell-shaped chamber (17), which opens toward the combustion chamber (10) and has an inside cross section that is substantially smaller than the combustion chamber (10), and that the injection and ignition take place in the bell-shaped chamber (17), the bell-shaped chamber (17) has a volume which amounts to approximately 30 to 50% of the minimum combustion chamber volume present at top dead center of the reciprocating piston (14), and turbulence edges are provided in the bell-shaped chamber 17 for making fuel and air turbulent. 
     
     
       16. An internal combustion engine in accordance with claim 15, in which the chamber (17) is embodied in the cylinder head (11). 
     
     
       17. An internal combustion engine in accordance with claim 15, in which a virtually symmetrical depression (24) is formed in the middle of the end wall of the reciprocating piston (14) that defines the combustion chamber (10), and this depression, together with the combustion chamber (10), adds to the bell shape of the chamber (17) to make a pear shape. 
     
     
       18. An internal combustion engine in accordance with claim 15, in which the fuel injection is controlled such that a fuel-air mixture formation takes place in the chamber (17) at idling and lower partial load, and in the chamber (17) and the combustion chamber (10) at upper partial load and full load. 
     
     
       19. An internal combustion engine in accordance with claim 15, which includes an injection nozzle (18) for the fuel injection and a spark plug (20) with an ignition electrode (201, 202) for the ignition, the injection nozzle and the spark plug being disposed in the cylinder head (11), the spark plug (20) and the injection nozzle (18) are oriented such that the ignition electrodes (201, 202) protruding into the chamber (17) are located outside the injection stream (21) of the injection nozzle (18).